<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>dom-事件</title>
</head>
<body>

<div class="container">
    <div id="message">welcome,<span id="username"></span></div>
    <button id="btnJump">跳转</button>
    <button id="btnAdd">添加</button>

    <label>城市：</label>
    <select id="slt">
        <option value="0">--所有城市--</option>
        <option value="1">天津</option>
        <option value="2">北京</option>
    </select>
</div>

</body>
<script>
    var num = '1';
    alert(typeof  num);

</script>
<script src="js/element-3.js"></script>

</html>